Olanzapine augmentation in treatment-resistant panic disorder: a 12-week, fixed-dose, open-label trial.

The purpose of our study was to evaluate the efficacy and tolerability of low-dose olanzapine augmentation in selective serotonin reuptake inhibitor (SSRI)-resistant panic disorder (PD) with or without agoraphobia. In this 12-week, open-label study, 31 adult outpatients with treatment-resistant PD who had previously failed to respond to SSRI treatment were treated with fixed dose of olanzapine (5 mg/d) in addition to SSRI. Efficacy was assessed using the Panic Attack and Anticipatory Anxiety Scale (PAAAS), the Agoraphobic Cognitions Questionnaire (ACQ), the Hamilton Rating Scale for Anxiety (HAM-A), the Hamilton Rating Scale for Depression (HAM-D), the Global Assessment of Functioning Scale (GAF), and the Clinical Global Impression of Improvement (CGI-I). Twenty-six patients completed the trial period with a dropout rate of 16.1%. At week 12, 21 patients were responders (81.8%), and an overall improvement on all rating scales was observed in all patients both with or without agoraphobia. Fifteen patients (57.7%) achieved remission. Olanzapine was well tolerated and the most frequent adverse effects were mild-to-moderate weight gain and drowsiness. No extrapyramidal symptoms were reported. Olanzapine appears to be effective as augmentation strategy in the treatment of SSRI-resistant PD, but study limitations must be considered and placebo-controlled studies are needed.